Saturday

A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades.[1][2] Centuries ago, windmills usually were used to mill grain, pump water, or both. Thus they often were gristmills, windpumps, or both.[3] The majority of modern windmills take the form of wind turbines used to generate electricity, or windpumps used to pump water, either for land drainage or to extract groundwater.

Windmills in antiquity

Heron’s wind-powered organ
The windwheel of the Greek engineer Heron of Alexandria in the first century is the earliest known instance of using a wind-driven wheel to power a machine.[4][5] Another early example of a wind-driven wheel was the prayer wheel, which has been used in Tibet and China since the fourth century.[6] It has been claimed that the Babylonian emperor Hammurabi planned to use wind power for his ambitious irrigation project in the seventeenth century BCE.[7]

Horizontal windmills

The Persian horizontal windmill

Hooper’s Mill, Margate, Kent, an eighteenth-century European horizontal windmill
The first practical windmills had sails that rotated in a horizontal plane, around a vertical axis.[8] According to Ahmad Y. al-Hassan, these panemone windmills were invented in eastern Persia as recorded by the Persian geographer Estakhri in the ninth century.[9][10] The authenticity of an earlier anecdote of a windmill involving the second caliph Umar (AD 634–644) is questioned on the grounds that it appears in a tenth-century document.[11] Made of six to 12 sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were quite different from the later European vertical windmills. Windmills were in widespread use across the Middle East and Central Asia, and later spread to China and India from there.[12]

A similar type of horizontal windmill with rectangular blades, used for irrigation, can also be found in thirteenth-century China (during the Jurchen Jin Dynasty in the north), introduced by the travels of Yelü Chucai to Turkestan in 1219.[13]

Horizontal windmills were built, in small numbers, in Europe during the 18th and nineteenth centuries,[8] for example Fowler’s Mill at Battersea in London, and Hooper’s Mill at Margate in Kent. These early modern examples seem not to have been directly influenced by the horizontal windmills of the Middle and Far East, but to have been independent inventions by engineers influenced by the Industrial Revolution.[14]

Vertical windmills

Due to a lack of evidence, debate occurs among historians as to whether or not Middle Eastern horizontal windmills triggered the original development of European windmills.[15][16][17][18] In northwestern Europe, the horizontal-axis or vertical windmill (so called due to the plane of the movement of its sails) is believed to date from the last quarter of the twelfth century in the triangle of northern France, eastern England and Flanders.[citation needed]

The earliest certain reference to a windmill in Europe (assumed to have been of the vertical type) dates from 1185, in the former village of Weedley in Yorkshire which was located at the southern tip of the Wold overlooking the Humber estuary.[19] A number of earlier, but less certainly dated, twelfth-century European sources referring to windmills have also been found.[20] These earliest mills were used to grind cereals.[citation needed]

A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades.[1][2] Centuries ago, windmills usually were used to mill grain, pump water, or both. Thus they often were gristmills, windpumps, or both.[3] The majority of modern windmills take the form of wind turbines used to generate electricity, or windpumps used to pump water, either for land drainage or to extract groundwater.

Windmills in antiquity

Heron’s wind-powered organ
The windwheel of the Greek engineer Heron of Alexandria in the first century is the earliest known instance of using a wind-driven wheel to power a machine.[4][5] Another early example of a wind-driven wheel was the prayer wheel, which has been used in Tibet and China since the fourth century.[6] It has been claimed that the Babylonian emperor Hammurabi planned to use wind power for his ambitious irrigation project in the seventeenth century BCE.[7]

Horizontal windmills

The Persian horizontal windmill

Hooper’s Mill, Margate, Kent, an eighteenth-century European horizontal windmill
The first practical windmills had sails that rotated in a horizontal plane, around a vertical axis.[8] According to Ahmad Y. al-Hassan, these panemone windmills were invented in eastern Persia as recorded by the Persian geographer Estakhri in the ninth century.[9][10] The authenticity of an earlier anecdote of a windmill involving the second caliph Umar (AD 634–644) is questioned on the grounds that it appears in a tenth-century document.[11] Made of six to 12 sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were quite different from the later European vertical windmills. Windmills were in widespread use across the Middle East and Central Asia, and later spread to China and India from there.[12]

A similar type of horizontal windmill with rectangular blades, used for irrigation, can also be found in thirteenth-century China (during the Jurchen Jin Dynasty in the north), introduced by the travels of Yelü Chucai to Turkestan in 1219.[13]

Horizontal windmills were built, in small numbers, in Europe during the 18th and nineteenth centuries,[8] for example Fowler’s Mill at Battersea in London, and Hooper’s Mill at Margate in Kent. These early modern examples seem not to have been directly influenced by the horizontal windmills of the Middle and Far East, but to have been independent inventions by engineers influenced by the Industrial Revolution.[14]

Vertical windmills

Due to a lack of evidence, debate occurs among historians as to whether or not Middle Eastern horizontal windmills triggered the original development of European windmills.[15][16][17][18] In northwestern Europe, the horizontal-axis or vertical windmill (so called due to the plane of the movement of its sails) is believed to date from the last quarter of the twelfth century in the triangle of northern France, eastern England and Flanders.[citation needed]

The earliest certain reference to a windmill in Europe (assumed to have been of the vertical type) dates from 1185, in the former village of Weedley in Yorkshire which was located at the southern tip of the Wold overlooking the Humber estuary.[19] A number of earlier, but less certainly dated, twelfth-century European sources referring to windmills have also been found.[20] These earliest mills were used to grind cereals.[citation needed]

A windmill is a mill that converts the energy of wind into rotational energy by means of vanes called sails or blades.[1][2] Centuries ago, windmills usually were used to mill grain, pump water, or both. Thus they often were gristmills, windpumps, or both.[3] The majority of modern windmills take the form of wind turbines used to generate electricity, or windpumps used to pump water, either for land drainage or to extract groundwater.

Windmills in antiquity

Heron’s wind-powered organ
The windwheel of the Greek engineer Heron of Alexandria in the first century is the earliest known instance of using a wind-driven wheel to power a machine.[4][5] Another early example of a wind-driven wheel was the prayer wheel, which has been used in Tibet and China since the fourth century.[6] It has been claimed that the Babylonian emperor Hammurabi planned to use wind power for his ambitious irrigation project in the seventeenth century BCE.[7]

Horizontal windmills

The Persian horizontal windmill

Hooper’s Mill, Margate, Kent, an eighteenth-century European horizontal windmill
The first practical windmills had sails that rotated in a horizontal plane, around a vertical axis.[8] According to Ahmad Y. al-Hassan, these panemone windmills were invented in eastern Persia as recorded by the Persian geographer Estakhri in the ninth century.[9][10] The authenticity of an earlier anecdote of a windmill involving the second caliph Umar (AD 634–644) is questioned on the grounds that it appears in a tenth-century document.[11] Made of six to 12 sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were quite different from the later European vertical windmills. Windmills were in widespread use across the Middle East and Central Asia, and later spread to China and India from there.[12]

A similar type of horizontal windmill with rectangular blades, used for irrigation, can also be found in thirteenth-century China (during the Jurchen Jin Dynasty in the north), introduced by the travels of Yelü Chucai to Turkestan in 1219.[13]

Horizontal windmills were built, in small numbers, in Europe during the 18th and nineteenth centuries,[8] for example Fowler’s Mill at Battersea in London, and Hooper’s Mill at Margate in Kent. These early modern examples seem not to have been directly influenced by the horizontal windmills of the Middle and Far East, but to have been independent inventions by engineers influenced by the Industrial Revolution.[14]

Vertical windmills

Due to a lack of evidence, debate occurs among historians as to whether or not Middle Eastern horizontal windmills triggered the original development of European windmills.[15][16][17][18] In northwestern Europe, the horizontal-axis or vertical windmill (so called due to the plane of the movement of its sails) is believed to date from the last quarter of the twelfth century in the triangle of northern France, eastern England and Flanders.[citation needed]

The earliest certain reference to a windmill in Europe (assumed to have been of the vertical type) dates from 1185, in the former village of Weedley in Yorkshire which was located at the southern tip of the Wold overlooking the Humber estuary.[19] A number of earlier, but less certainly dated, twelfth-century European sources referring to windmills have also been found.[20] These earliest mills were used to grind cereals.[citation needed]